45 



■which may be found to be infested, so that the eggs and maggots may be destroyed ; 

 (c) deep ploughing by which loose puparia, or infested stubble may be buried too deeply in 

 the ground to allow the perfect flies to emerge. 



From the historical sketch which is given of the occurrence of C. destructor, it would 

 appear that although a watch has been kept upon it since its first outburst as a destruc- 

 tive scourge in North America, in the year 1786, it had never been actually identified as 

 occurring in Great Britain until July, 1 886. 



The large number of widely separated localities, however, from which its ravages 

 have now been reported, might lead one to the conclusion, either that it must have been 

 established for some time previous to that date, and that it was only Miss Ormerod's 

 energy and zeal which then brought its operations to light ; or that some special circum- 

 stance has taken place during the past summer by which it has been distributed over the whole 

 kingdom ; or again, that some special climatic condition has allowed it to exist where it 

 had failed to do so before. For several years Miss Ormerod has had an active and 

 observant body ol intelligent workers in all quarters of Great Britain, and it is strange, if 

 it existed at all, that nothing has been heard previously of its operations. Nevertheless, 

 on the other hand, from the large quantities of straw and seed grain imported annually 

 into the British Isles from countries known to be infested by this fly, together with the 

 present rapid and easy methods of transport, it is at least extremely probable that it has: 

 been introduced over and over again, and it is difficult to understand why it has not long 

 before now secured a firm foothold there. May it not be hoped that the law which applies 

 with regard to many noxious weeds, will also be found to hold good in the case of this 

 injurious insect ? 



The existence of any plant as an aggressive weed in a given locality, appears to be 

 not so much a question of the introduction of the seed, as of the plant finding there the 

 conditions suitable to its growth and healthy reproduction. There are many plants, for 

 instance, troublesome weeds here, which must have been frequently introduced into 

 Europe from this Continent, (or in some instances taken back again to the place whence 

 we originally received them), but which have never yet taken forcible possession of culti-- 

 vated ground, e. g, the Common Purslane (Portulaca oleracea), Hound's Tongue or Burrs 

 (Cynoglossum officinale), Small Burrs (Echinospermum Lappula), and the common Fox-. 

 tail Grasses (Setaria glauca and viridis) ; and then, although relatively they are far 

 fewer, there are some which must have been frequently introduced on this continent, but 

 which, except in a few localities, cannot (or do not) exist for more than two or three 

 seasons, e. g, the Common Scaidet Corn Poppy (Papaver Rliceas), Scarlet Pimpernel 

 (Anagallis arvensis), Common Groundsel (Senecio vulgaris), Corn Gromwell (Litho- 

 spermum arvense), and the Common Nettles (Urtica dioica and U. tcrens). In the same 

 way there is no doubt whatever, that the Colorado potato bettle (Doryphora 10-lineata), 

 has been many times conveyed to the British Isles on transatlantic steamships ; but not. 

 finding there conditions suitable to its requirements it has failed to establish itself. 



Miss Ormerod, quoting from Bulletin 4, U. S. Ent. Com., tells us that "the original 

 habitat of the Hessian fly is considered most probably to have been Southern Europe and 

 "Western Asia, i. e., about the shores of the Mediterranean Sea," a district with a summer 

 climate of far greater heat and aridity than is found in the British Islands. Again, in 

 North America, where, whether introduced or indigenous matters not in this connection, 

 this pest to our sorrow flourishes to a most remarkable degree, it has always dry, hot 

 weather during the periods in which it passes through its active stages. 



In view of the above facts, and notwithstanding that it has occurred in considerable 

 numbers in many parts of Great Britain during the past summer, I think it probable that 

 its widespread appearance as an injurious insect, was due either to some special cause 

 which had not existed before, or to some unusual climatic condition, rather than to its 

 having established itself in a new habitat suitable to its reproduction and increase. 

 Furthermore, if the farmers can only be frightened sufficiently to induce them to 

 obtain the pamphlet under consideration, and to follow closely the advice which is there 

 offered them, I cannot help thinking that before very long Miss Ormerod will be able to. 

 relegate the Hessian fly to a place amongst the foes she has conquered. 



